I very much doubt there is one... We don't even have information from the books to form a comprehensive list, I think. Whether a group is a signatory or not can take a while to come up - for instance while the Order of the Blackened Denarius are signatories, that isn't mentioned in Death Masks IIRC. It takes until Small Favor, the second Denarian-focused book until we get that info. There might be a list of known Freeholding Lords, though. They're at least enumerated pretty clearly in the books...
Signatory Nations (not the Freeholds) off the top of my head:
White Council
The Vampire Courts (unknown if they're signed on collectively or independently. Might actually be collectively as the war is between the Council and the Vampire Courts, not just the Reds. The Whites just really slack on the war effort.)
The Faerie Courts
The Denarians
The Fomor